78 Mr. T. II. Withers on 



C. caretta affix themselves to the surface of the turtle to- 

 day." 



Although many specimens have been found attached to 

 ammonites, in no case am I aware that tliey are attached to 

 the actual shell, the ammonite being represented by a chalk- 

 cast. AVhatevcr the mode of attachment, it cannot be said to 

 he truly comparable to the mode of attachment of Coronula 

 or Chelunibia. To my mind it is more probable that tlie shell of 

 Stramentumwa.s attached only by the extremity of its peduncle, 

 and was pressed against the side of the ammonite during 

 fossilization. While the Kansas examples of Siramenliun 

 haioorthi on the two slabs iu the Geological Department of 

 the British Museum appear to have been attached to a strap- 

 like organism, of which only a stain remains, the type was 

 said by Logan to be attached to a shell of Ostreu cunyesta 

 by the extremity of its j)edunclc. Dr. H. Woodward ap[)ears 

 to have doubted this, but there is a jjhotograph of the type 

 exhibited with the above-mentioned slabs in the British 

 Museum, and this conclusively shows that that specimen, at 

 any rate, was so attached. 



Comparison with other Genera and Phyloijenelic Position. 



The structure of Stramenticni as now revealed by the new 

 material certainly shows it to be more anomalous than was 

 thought. So far as our knowledge goes, it dillers from all 

 otiier cirripedes, both recent and fossil, in that all the valves 

 of the capitulnm arc paired, and that the outermost oi' sub- 

 carinal and subscutal rows of peduncular plates do not 

 overlap or intersect each other. Tlie shell could therefore 

 readily be divided along the sutures formed aloug the 

 carina] and scutal margins. It further differs from all 

 recent cirripedes in the marked disparity in size of the 

 lateral plates of the peduncle as compared with those of the 

 subscutal and subcarinal series. There ajjpears to be a 

 similar disposition of the peduncular plates in the Cretaceous 

 genera >S(/?/a?;/«(Senonian) and Luriculina (Seiionian). How 

 far these genera are related it is dillicult to say,' for we 

 know so little of their precise structure. Further investiga- 

 tion may prove Loricnlina to be congeneric with Strunientiim, 

 for the presence of a comi)aratively large robtrum in the 

 ligure o( the genotyi)e may not be subsiantialcd. ii<juunia, 

 which is so far contined to the Kansas elnilk and occurs at a 

 slightly lower liorizon than Sirumcntuju huworthi, is known 

 (uily IVom the inadctjuale figures and descriptions of Logan. 

 When the jjiecise structure of the genus is known it will 



